$ git clone -n https://src.fedoraproject.org/rpms/m4.git /var/lib/mock/f45-build-17893-505/root/chroot_tmpdir/scmroot/m4
Cloning into '/var/lib/mock/f45-build-17893-505/root/chroot_tmpdir/scmroot/m4'...
$ git fetch origin d91104adeb7f2ca880ec3cb7d5bd6bbcf2d7c9d0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/m4
 * [new ref]         d91104adeb7f2ca880ec3cb7d5bd6bbcf2d7c9d0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d91104a Fix SIGSEGV in gnulib posix_spawn_file_actions_addchdir tests